1. Field of the Invention
The present invention relates generally to a clutch control system for a transmission. More particularly, to a clutch control system for a transmission that can detect the fact that hydraulic control during shifting is not executed as previously planned by detecting an input-output speed ratio of the transmission to appropriately deal with such an event. In addition, the present invention generally relates to gear shift control apparatuses for a motorcycle. More particularly, to a gear shift control apparatus that detects the turning state of the vehicle based on a difference in rotational speed between front and rear wheels for prohibiting automatic gear shifting.
2. Description of Background Art
A transmission is known that includes a hydraulic pump driven by the rotational drive force of an engine and exercises engagement-disengagement control on a clutch by the hydraulic pressure generated by the hydraulic pump.
Japanese Patent Laid-Open No. Hei 11-82720 discloses a clutch control system for a 4-step speed-change type transmission including first through fourth clutches corresponding respectively to first-speed through fourth-speed gears. To drive the four clutches, this system can allow three shift valves to switch oil passages per se adapted to supply hydraulic pressure.
The clutch control system for a transmission disclosed in Japanese Patent Laid-Open No. Hei 11-82720 includes the shift valves as mentioned above as well as electromagnetic valves adapted to control supply of hydraulic pressure to the oil passages. Therefore, this system can individually control the four clutches. Consequently, even in the event wherein one electromagnetic valve causes a failure, the oil passage per se can be switched to another system to complete the shifting operation.
On the other hand, there is known a twin clutch type transmission that includes an electromagnetic valve used to alternately supply the hydraulic pressure generated by a hydraulic pump to two hydraulic clutches and executes shifting to an adjacent gear step by switching the operation of clutches wherein the supply destination of hydraulic pressure is switched from one of the clutches to the other. This twin clutch type transmission can reduce the number of component parts for hydraulic control to simplify the configuration of oil passages, thereby achieving downsizing and weight reduction of the transmission.
However, the twin clutch type transmission as mentioned above is not provided with a shift valve for switching the oil passages per se. Therefore, when the supply destination of hydraulic pressure is switched from one of the clutches to the other by the clutch switching operation, the hydraulic pressure of the one of the clutches may not be lowered due to any cause. In such a case, there is a possibility that both the clutches may simultaneously come into the engagement state along with the supply of hydraulic pressure to the other of the clutches. When the supply destination of hydraulic pressure is switched from one of the clutches to the other by the clutch switching operation, the hydraulic pressure of the other clutch may not increase due to any cause. In such a case, there is a possibility that the shifting operation may appropriately not be completed.
The invention described in Japanese Patent Laid-Open No. Hei 11-82720 can switch the oil passage per se to the separate system using the shift valve. Therefore, it does not make consideration of the problem specific to the twin clutch type transmission having the configuration described above.
An automatic gear shifting is known wherein a prohibition of the automatic gear shifting occurs during a turning maneuver (cornering) of a vehicle in a gear shift control apparatus that executes an automatic gear shifting on a transmission in response to vehicle speed or engine speed.
Japanese Patent Laid-Open No. 2007-107667 discloses an automatic gear shifting control apparatus for a four-wheeled vehicle configured to prohibit an automatic gear shifting by detecting the vehicle during a turning maneuver on the basis of a difference in rotational speed between left and right wheels.
However, the gear shift control apparatus of Japanese Patent Laid-Open No. 2007-107667 detects a turning state on the basis of the rotational speed difference between the left and right wheels of the four-wheeled vehicle. Japanese Patent Laid-Open No. 2007-107667 does not discuss the detection of such a turning state applied to motorcycles having only a front and a rear wheel aligned with each other in the back and forth direction of a vehicle body.